From fd3a9025c0349bc9b01d627529f54e6e1e389015 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Wed, 27 Feb 2013 17:53:52 -0800 Subject: [PATCH] iscsi-target: Fix immediate queue starvation regression with DATAIN This patch addresses a v3.5+ regression in iscsi-target where TX thread process context -> handle_response_queue() execution is allowed to run unbounded while servicing constant outgoing flow of ISTATE_SEND_DATAIN response state. This ends up preventing memory release of StatSN acknowledged commands in a timely manner when under heavy large block streaming DATAIN workloads. The regression bug was initially introduced with: commit 6f3c0e69a9c20441bdc6d3b2d18b83b244384ec6 Author: Andy Grover Date: Tue Apr 3 15:51:09 2012 -0700 target/iscsi: Refactor target_tx_thread immediate+response queue loops Go ahead and follow original iscsi_target_tx_thread() logic and check to break for immediate queue processing after each DataIN Sequence and/or Response PDU has been sent. Reported-by: Benjamin ESTRABAUD Cc: Andy Grover Cc: Signed-off-by: Nicholas Bellinger --- drivers/target/iscsi/iscsi_target.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 23a98e658306..af77396234a2 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -3583,6 +3583,10 @@ check_rsp_state: spin_lock_bh(&cmd->istate_lock); cmd->i_state = ISTATE_SENT_STATUS; spin_unlock_bh(&cmd->istate_lock); + + if (atomic_read(&conn->check_immediate_queue)) + return 1; + continue; } else if (ret == 2) { /* Still must send status, @@ -3672,7 +3676,7 @@ check_rsp_state: } if (atomic_read(&conn->check_immediate_queue)) - break; + return 1; } return 0; @@ -3716,12 +3720,15 @@ restart: signal_pending(current)) goto transport_err; +get_immediate: ret = handle_immediate_queue(conn); if (ret < 0) goto transport_err; ret = handle_response_queue(conn); - if (ret == -EAGAIN) + if (ret == 1) + goto get_immediate; + else if (ret == -EAGAIN) goto restart; else if (ret < 0) goto transport_err; -- 2.39.5